1. Field of the Invention
The present invention relates to a waterproof device and a portable timepiece including a push-in operation portion waterproof property of which is improved.
2. Description of the Related Art
In portable devices including portable timepieces such as a wrist watch and a pocket watch, a stopwatch, a cellular phone and a portable information terminal device, there are devices, for example, including an operation member such as a push button for operating contacts in a device outer housing, which is attached to the device outer housing. In such device, given functions are executed when the push button is pushed given times of strokes. For example, in the portable timepiece, a dial window can be illuminated, a timepiece display can be switched from an analog display to a digital display or can be inversely switched and further, the date or the day of the week which is digitally displayed can be modified.
As a shaft portion of the push button pierces the device outer housing from inside to outside in such kind of portable device, it is necessary to waterproof a portion at which the push button is formed (push-in operation portion).
In order to realize the above, a structure of waterproofing between the shaft portion of the push button and the device outer housing by fitting a seal material which has a ring shape and can be elastically deformed to the outer periphery of the shaft portion of the push button piercing a pipe fixed to the device outer housing, and allowing the seal material to be closely contacted with an inner surface of the pipe in a state where the seal material is compressed in a radial direction (refer to JP-A-2004-319446 (Patent Literature 1)).
There is also provided a method of attaching a waterproof switch member for pressing a switch inside a device casing to the casing as well as combining a push button with the waterproof switch member to thereby perform the waterproofing (for example, refer to JP-A-2011-258334 (Patent Literature 2)).
Specifically, the waterproof switch member is made of an elastic material, having an opening and a container part protruding on the opposite side of the opening. The switch member is attached to the casing in a state where the container part is inserted into a through hole formed in the casing so as to face the switch, in which the push button is arranged in a state where a shaft is inserted into an inside space of the container part so that the shaft pushes a bottom portion of the container part. Accordingly, the waterproofing from the inside space of the container part to the outside is realized by the container part. Moreover, the container part has a loop-shaped rib formed continuously formed along the outer periphery thereof. The rib is provided in a deformed state by receiving compression from an inner wall of the through hole. Accordingly, the waterproofing between the inner wall of the through hole and an outer peripheral surface of the container part is realized. When the push button is pushed, the bottom potion and a side portion of the container part extend toward the switch to thereby press the switch.
In the waterproof structure described in Patent Literature 1, when the push button is moved in an axial direction, the seal material slides along an inner surface of the pipe. Accordingly, for example, under a condition in which the portable device is exposed to water, for example, in the case where the push button is operated in water, the sealing performance becomes unstable because the portion sealed by the seal material is moved with the push button. Accordingly, there is a danger that the waterproof performance is reduced at a portion where the push button is arranged.
Also in the waterproof structure described in Patent Literature 2, there is a similar concern about waterproof property. That is, when the push button is pushed, the rib formed along the outer periphery of the side portion slides along the inner wall of the through hole as the side portion of the container part extends toward the switch. Accordingly, for example, when the push-in operation of the push button is performed in water and the like, seal performance for the waterproofing becomes unstable as the rip is moved with the push button. Accordingly, there is a danger that the waterproof performance is reduced at a portion where the push button is arranged.
The related art techniques have problems that there is room for improvement on the waterproof property around the push button.